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Major Help Needed!!!!

Ok......I bought a David Weekley home back in May 2007 and we are still having problems with our A/C. We live in southwest Houston in a 2 story 3400 sq foot home that has 2 A/C units. Here is what I know....

We had the compressor on the upstairs unit burn out already and had to be replaced. The issue we are mainly having is the downstairs master bedroom will cool off but the rest of the downstairs won't. There is usually a 4 to 7 degree differential most of the time (even at midnight). Since we have been complaining about since we moved in we are still somewhat covered under warranty. We had Fresh Air and 2 other companies come out to take a look and they all basically said the following :

- The A/C tonage is not big enough to compensate for the square footage of the house and that's why it's not cooling down
- There is very minimal air flow in the kitchen/living room which is causing another problem
- The evaporator coils being 4 ton and the units being 3 is another issue
- With the heat load and all the windows we have the units aren't capable of handling the load

We need to have more tonage outside, need to add more vents in the kitchen/living room and need to adjust the only 2 vents in the living room. Well of course Weekley is balking at this now (when the warranty project manager agreed to pay for the work to be done...and I have this on voicemail) and they sent out Davis A/C to come and take a look at it. They are going to set up sensors to record all the temperature data for 5 days to look and see if they can resolve the issue. Weekley states that homes are built to spec using a J manual, which is supposed to prevent things like this from happeneing but I don't trust them. I have had enough people look and tell me what's wrong (besides living in the house myself) to know that the A/C is not (and has never) working properly. It could be march in the evening time and I can set the thermostats to 65 degrees and the A/C system won't cool off below 74....and this is not in the heat of the summer. I feel that Davis is going to be "preped" by Weekley and they will come back with "everything is just fine" scenario and trying to make it seem like there is nothing wrong with the A/C.

Ok......I bought a David Weekley home back in May 2007 and we are still having problems with our A/C. We live in southwest Houston in a 2 story 3400 sq foot home that has 2 A/C units. Here is what I know....

We had the compressor on the upstairs unit burn out already and had to be replaced. The issue we are mainly having is the downstairs master bedroom will cool off but the rest of the downstairs won't. There is usually a 4 to 7 degree differential most of the time (even at midnight). Since we have been complaining about since we moved in we are still somewhat covered under warranty. We had Fresh Air and 2 other companies come out to take a look and they all basically said the following :

- The A/C tonage is not big enough to compensate for the square footage of the house and that's why it's not cooling down
- There is very minimal air flow in the kitchen/living room which is causing another problem
- The evaporator coils being 4 ton and the units being 3 is another issue
- With the heat load and all the windows we have the units aren't capable of handling the load

We need to have more tonage outside, need to add more vents in the kitchen/living room and need to adjust the only 2 vents in the living room. Well of course Weekley is balking at this now (when the warranty project manager agreed to pay for the work to be done...and I have this on voicemail) and they sent out Davis A/C to come and take a look at it. They are going to set up sensors to record all the temperature data for 5 days to look and see if they can resolve the issue. Weekley states that homes are built to spec using a J manual, which is supposed to prevent things like this from happeneing but I don't trust them. I have had enough people look and tell me what's wrong (besides living in the house myself) to know that the A/C is not (and has never) working properly. It could be march in the evening time and I can set the thermostats to 65 degrees and the A/C system won't cool off below 74....and this is not in the heat of the summer. I feel that Davis is going to be "preped" by Weekley and they will come back with "everything is just fine" scenario and trying to make it seem like there is nothing wrong with the A/C.

- The A/C tonage is not big enough to compensate for the square footage of the house and that's why it's not cooling down
- There is very minimal air flow in the kitchen/living room which is causing another problem
- The evaporator coils being 4 ton and the units being 3 is another issue
- With the heat load and all the windows we have the units aren't capable of handling the load

I would present this information to the builder and ask that they make everything right.

If the builder is telling you that they use the manual J to determine the total heat load on the home, ask for a copy of it. The load calculation will also determine how many CFM need to be provided to each and every room. With that information the installer should know what size ducts to run and where.

A 3 ton condenser on a 4 ton evaporator is not good practice. The system needs to be properly matched. Also check the BBB for any reports on the company that performed the install. This may help you in your battle against the builder. Also if the builder agrees to pay to make it right, you should choose your own HVAC contractor. Don’t let them tell you who THEY want to use. Its YOUR home.

Thanks to all of you for helping me....I am so frustrated that I am ready to pull my hair out 1 strand at a time.

I am not sure what Jabarco meant...I am a moron. Can someone please explain that to me in simpleton terms.

Thanks!

Sometimes showing is better than telling, his scale shows the btu rating for your system in cooling. Notice the slide set at 36,000. There may be another problem such as noncondensables. It may be better to have a second opinion even if you have to pay for it yourself. Im not a big fan of builders, some do a very good job, some dont.

IMO, with Retro-work, that unit can be made to do the job in that home

- The A/C tonage is not big enough to compensate for the square footage of the house and that's why it's not cooling down
- There is very minimal air flow in the kitchen/living room which is causing another problem
- The evaporator coils being 4 ton and the units being 3 is another issue
- With the heat load and all the windows we have the units aren't capable of handling the load
==========================================
Off hand, I would postulate that the problem is with the duct system & lack of a proper airflow heatload through the evaporator coil.

Checking the condenser discharge air temperature compared to the OAT would show us what heatload the evaporator is delivering to the condenser.

Could be pulling hot attic air into the Return, for all we know.

I would look at what BTUH of heatload the ductwork & airflow calls for in each room & run SA & RA to remove that heatload to & through the evaporator coil.

If some rooms need retro-work to reduce the heatload, if cost effective, do the work.

The unit was engineered to work okay with a 4-ton evaporator; I don't believe that is the problem.

At 67-F wet bulb & 1200-cfm I see design is 35.2-BTUH; [CX34−44/48B/C−6F] [C33−48B/C] is that the wrong coil?

This is guesswork because we don't have enough data to know what we are dealing with here. However, I will state, that with Retro-work, that unit can be made to do the job in that home. - Darrell

Great advice from all. Have a system capacity test done. Have them make sure your duct system is tight. I mastic all my systems. You can lose alot of capacity thru duct leakage from ducts. A Manual J of each room will tell them how much air each space needs. Have them do a Manual D and check it against your duct design. Most new construction I see have way to small ducting. This may not be your case.

In most cases, when a 4 ton coil is used with a 3 ton condensing unit it boost capacity beyond 3 tons as well as SEER. However, the data shows Lennox doesn't boost capacity. Instead, it appears that the capacity doesn't even equal 36,000 btu/hr. (max @ 35,600 @ ARI Ratings). However, the SEER is 15 when using this 14 SEER condensing unit.

I prefer comfort. Therefore, if it were my system, I’d tell the builder to take his 3 ton condensing units rated @ 15 SEER and shove 'em up his horse's ass........give me the 4 ton condensing units that matches my 4 ton coils!

Jabs

I didn't see any real model numbers posted so it could be that the 4 ton coils are a match for the 3 ton condensors. May be that a 4 ton unit would need a 5 ton coil? Also the duct may already not be sized right and jumping to a 4 ton would just make matters worse.

If we can get the exact model numbers for the outdoor and indoor units we could give exact numbers.